Switching circuits have been proposed in which the fog lights are switched off when the headlights are switched on by means of relays or through a combination of relays with an additional electronic connection.
In the case of the simple relay circuit proposed, the relay is connected as a normally-closed relay, so that the coil of the relay is connected in parallel with the headlights to a headlight lead and so that the contact of the relay is in series with the fog lights to a fog light lead. As soon as the headlights are switched on, the battery voltage is applied to the relay coil and the break contact is actuated. The current supplied to the fog lights is thus interrupted and the fog lights are thus switched off. This connection has the shortcoming that an expensive special relay must be inserted because there is no standardized vehicle relay that can switch the corresponding lamp load with the break contact.
With an additional electronic circuit the relay can be used as a normally-open relay. The electronics are constructed so that the make contact of the relay is closed with the fog lights switched on and thus the fog lights are switched on.
As soon as the headlights are activated, the electronics open the current circuit to the relay coil so that the make contact is opened and the fog lights are switched off. The disadvantage of both switching circuits lies in the need to use special structural components or additional electronics that make the switching complicated and more expensive.
The invention proposes the construction of a switching circuit of the above-mentioned type in a cost-favorable and simple manner.